1. Field of the Invention
The present invention relates generally to detection of hydrocarbon vapor in air. More particularly, the present invention relates to apparatus configured to sense selected concentrations of particular gases and to provide a user of such apparatus with information relating to the concentration of the particular gas or gases sensed.
2. Description of the Related Art
Several styles of detectors are available for use, for example, in the automobile repair industry. Such detectors include those for halogenated hydrocarbons, particularly air conditioning coolants, for carbon dioxide, for carbon monoxide, for unburned gasoline components in an exhaust stream, and for a variety of others. Automobile systems include other sensors, such as intake mass density, oxygen content in exhaust, and the like, that are used in conjunction with a processor to permit dynamic adjustment of fuel/air mixture, for example, in order to prevent preignition, compensate for altitude, etc.
Rapid detection of several relatively low specific gravity combustible gases at low concentrations is desirable and has been possible with varying success and convenience. Existing apparatus for this function may be physically large and/or heavy, may have relatively poor sensitivity in terms of concentration or variety of gases the apparatus can detect, may provide limited information regarding hazard severity, may respond slowly to changes in concentration, may halt operation with scant warning, may allow only short battery life, may require repeated replacement of short-lived single-use (i.e., primary) batteries, etc.
Any instrument in this general category that is to be used in work environments having potential to endanger health and life of users must be approved by a recognized testing agency for the country or geographic region of use. For example, in the United States, Underwriters Laboratories® is authorized to perform testing and certification that allows specific instruments to be used in workshops that operate under the purview of the U.S. Occupational Safety and Health Administration (OSHA) and certain other Federal agencies. Equivalent approvals are required in most countries or regions (the latter including the European Union).
What is desired in the art is a compact, highly sensitive combustible gas detection apparatus.